Never have two gay policemen been so highly valued. A mural by Britain’s favourite guerrilla graffiti artist is to be taken across the Atlantic and sold at auction for an estimated £1 million.

The mural of two bobbies embracing, one of Banksy’s most famous and controversial works, has been a Brighton landmark for several years. Painted on the wall of the Prince Albert pub in 2004, next to George Best, the mural became a lure* for hundreds of art lovers from across the world as well as a few homophobes*.

After being attacked on many occasions with black spray paint, the life-size stencil* was covered in Perspex* to protect it. Chris Steward, the owner of the Prince Albert, then secretly removed the original and replaced it with a copy three years ago.

Mr Steward said that the decision had now been taken that it was time for the policemen to leave Brighton and head for New York. Experts have estimated that the private dealer handling the sale could secure £1 million for the mural. Mr Steward said that the money would go to the pub.

Banksy’s works have gained increasing cachet* over the years, even though much of the mystique surrounding the artist has faded. Celebrities including Brad Pitt and Angelina Jolie have bought his works.

Banksy was eventually identified by the media as Robin Cunningham, a Bristol-born former public schoolboy. His wife, a parliamentary lobbyist and former researcher for a Labour MP, was exposed this year by a Sunday newspaper.

His distinctive and irreverent* murals now pop up in Los Angeles. They include a drunk Mickey Mouse holding a cocktail and draped over a model, and the cartoon character Charlie Brown languidly* smoking a cigarette.

His Oscar nomination this year for Best Documentary Feature for his film Exit through the Gift Shop is expected to send prices for his works soaring. This year Sotheby’s in London sold one of his works, Heavy Weaponry, an image of an elephant with a rocket on its back, for £82,250. His top-selling work is Keep It Spotless, a Damien Hirst spot painting defaced with a chambermaid apparently lifting up the bottom of the canvas. It was sold in New York for $1.87 million (£1.13 million) in 2008.